Exhaust Repair

[iajim]

I was wondering if anyone has repaired an expansion chamber using heat(torch) and compressed air to remove dents. I realize this is something that could get very dangerous. Is 1 or 2 psi enough pressure? What would be the best mechanism for plugging the two openings? Is a mapp gas torch enough heat or is an Oxy-acetylene set up required? Any advice, direction or horror stories of what went wrong would be greatly appreciated.

[webmaster]

FYI - It isn't that expensive to send it to pacific crest pipe repair and have it professionally done.

www.piperepair.com

Others using the expansion of freezing water to pop out dents - e.g. fill it partially with water - plug the ends (plumbing fittings) and throw it in the freezer...

jeff



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[GMP]

My friend Cruiser has experience in these matters, perhaps he will comment. I know he told me he launched a plug across the shop once!

[HuskyDude]

Those picture on the Pacific Crest site are amazing.

I've done the PSI and torch thing. It was with a acetylene touch only for soldering pipe. Propane will work too but you need a big tip. It happens pretty quick so less psi the better. These were for small dents nothing like those pictures...
I've also heard of riders using water then place your expansion pipe in the freezer. Water expands into ice...etc. Again for smaller dents.

[gasgasman]

Pacific Crest does a wonderful job. But, they do NOT have a Gas Gas pipe jig. So you will have to do some minor tweaking to make your pipe fit properly.

[Rick]

I have used Pacific Crest Pipe repair several times with excellent results. My Messico pipe has been retuned to me and bolts right up. They do a great job!

[eddy field1]

ive done this before using a propane torch and had to use almost 50 psi!! but the ideal pressure is ment to be around 20-30 psi this should be fine with oxyacetylene as it will obviously get it alot hotter. My friend has even gone as high as 100 psi glad i wasn't there!!!! his pipe dint explode so you should be ok but i would say 1,2 psi probebley wont do it
I think the water thing is for 4st pipes as it can crack the welds on a 2st

[stainlesscycle]

the water thing has issues - if you fill a pipe up with water and freeze it, it will expand all over evenly (or at the metals weakest spot...) not just at the ding. there's a chance that it will actually work, but there's a chance you'll end up with a misshapen pipe... pacific crest pipe repair is cheap...

[Cruiser]

Warning!! you have to either clean the inside of the pipe very well or use an inert gas!! I do this repair on occasion and I use argon to pressurize the pipes,, using regular air you can have a bomb.. the residue from the 2stroke fuel can heat up and catch fire or actually blow.. had a pipe blow the plug across the shop and shot a flame 10 feet.. the guy that was helping me had no hair left on his arm and some of one eyebrow singed.. If you dont have argon soak the pipe with a simple green or similar and wash out good.. If you know someone at a machine shop have it hot tanked then no worries..

[rpduc]

I've done this a couple times with pretty good results.

I use regular compressed air and mapp gas torch. I heated the pipe up real well in the dented areas with the pipe open to burn off any fumes. Then washed it out with degreaser and water a couple times.

Low psi did nothing in my case. I actually had the thing up over 100 psi after adding heat. I shot out a 8 ft. fluorescent tube when the expansion plug blew out of the small end but that was because I didn't clean the spooge out very well before hand. Second try I cleaned up the end and the plug well with acetone and made sure she was aimed at something less fragile. It held over 100 psi.

After that experience I'd personally would feel plenty safe at 50 - 60 psi but YMMV. For sure try more heat at lower pressure first. Maybe a bigger torch applying heat over a larger area would be safer and more effective, but the mapp gas will get a pretty good sized area cherry red. Maybe I was impatient and things might have moved at a lower pressure. Most Google "articles" seem to suggest that lower pressures are effective.

You can get rubber expansion plugs to fit the small end at any hardware store. I made a pressurizing clamp/plug for the big end out of a schrader valve test fitting (also from the hardware store), a pressure guage and some 1/4" plate. If you Google 2 Stroke pipe repair you should find pics of various contraptions that can be cobbled together.